import java.util.Scanner;

public class homework {

    //javaSE测试编程题：输出字符串包含的字符集合
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        StringBuffer sb = new StringBuffer();
        String str = scanner.next();
        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
            if(!sb.toString().contains(ch+"")){
                sb.append(ch);
            }
        }
        System.out.println(sb);
    }

}

